CS 334: Principles of Operating
System
An Introduction
Course Information
Course Name: Principles of Operating Systems
Course Code: CS 334
Course Type: Core, 12 credits
Course Description: This course is tailored to develop an understanding of operating
system core concepts.
Mode of Delivery: 2 hours lecture, 1 hour practical per week.
Lecture Session: Tuesday 1600 hrs, room B302
Practical Session: Tuesday 0800 hrs, room D01
Course Instructor: Anthony Kigombola, A107, kigombola@gmail.com
Course Assistant: Henry Mkama,
Prerequisites: CS 151: Computer Organization and Architecture I and
CS 252: Computer Organization and Architecture II
Course Outline
Lecture 1: Introduction
Course Information
Introduction to Operating Systems
Lecture 2: Process management
Process Life cycle
Process Scheduling
Process Synchronization
Threads and Multithreading
Lecture 3: Memory management
Memory Allocation
Paging
Segmentation
Virtual Memory
Course Outline
Lecture 4: File Management
Lecture 5: I/O management
Lecture 6: Deadlocks
Lecture 7: Security and Control
Lecture 8: OS Design
Practical
P1 Investigating Deadlocks
P2 Process States and Memory Management
P3 Process Synchronization
P4 Process Scheduling
P5 Memory Management
Case Studies
Assessment
Week Assessments Marks
6 Test 1 15%
12 Test 2 15%
3 - 12 Practicals/Use Cases 10%
16 or 17 Final Exam 60%
Textbooks/References
1. Modern Operating System, 4th edition, by Tannenbaum, A.S.,
Prentice-Hall
2. Operating System Concepts, 10th edition , by Silberschatz, A.,
Galvan,B. P., & Gagne, G.
3. Principles of Operating System, by Naresh Chauhan, Oxford
University Press
Introduction to Operating System
By the end of this lecture, you will have gained knowledge of the
following topics.
i. Operating System Overview
ii. History of Operating Systems
iii. Types of Operating Systems
iv. General Concepts on Operating Systems
Introduction to Operating Systems
• There was a time in the history of computers when user
programs were operating directly on the machine.
• Given the complexity of the machine, it was very
cumbersome to write a computer program that, apart
from solving a business process, it should also manage
the processor, memory, disk, mouse, keyboard and
display.
• Therefore, a software was designed, which worked on
the hardware to relieve applications and programmers
from the machine view of the system.
• The software did all the functionalities that needed to be
performed on the hardware, on behalf of the user.
• This software that operates the computer system is
known as an Operating System (OS)
Introduction to Operating System
• An Operating System (OS) is a software layer that sits
between user programs and computer hardware. OS
abstracts hardware resources and provides to application
programs a clean view of the resources.
Introduction to Operating System
OS functions can be summarized into two main functions
1. Computer Hardware Abstraction. The architecture
(instruction set, memory organization, I/O, and bus
structure) of most computers at the machine-language
level is primitive and complex. Abstraction hides all this
complexity and presents to users and application
programs a neat and friendly environment to work in.
2. Computer Resource Management. Another main
function of the operating system is to provide an
orderly and controlled allocation of the processors,
memories, and I/O devices among the various programs
wanting to use them.
History of Operating Systems
1. As OS are closely tied to the underlying computer
architecture, the changes in computer architecture
have had an impact on the design of OS.
2. We trace the history of OS based on the generations of
computers
Generations of Computers
Generation Period Technology
1st Gen 1945 -1955 Vacuum Tube
2nd Gen 1955 - 1965 Transistor
3rd Gen 1975 - 1980 Integrated Circuits
4th Gen 1980 - Present Microprocessors
5th Gen 1990 - Present Mobile Computing
History of Operating Systems
The First Generation (1945 – 1955)
• Computers in this generation were based on vacuum
tubes e.g. Z3 built by Konrad Zuse, ENIAC by William
Mauchley, Colossus by Alan Turing and Mark 1 built by
Howard Aiken.
• All programming was done in machine language by
wiring up electrical circuits using cables and plugboard
• There were no Operating Systems no programming
languages
History of Operating Systems
The Second Generation (1955 – 1965)
• With the introduction of transistors in the 1950s, computers
were transformed, resulting in the development of more
robust machines called mainframes.
• Programming was done on paper e.g. using FORTRAN and
punched into cards before being loaded onto computers with
a card reader
• Operating systems were introduced in this generation e.g.
IBSYS and FORTRAN Monitor System (FMS)
• Batch computing was also introduced to increase the
efficiency of the computing system
History of Operating Systems
The Third Generation (1965 – 1980)
• The introduction of Integrated Circuits (ICs) introduced a
huge price-performance advantage.
• With ICs it was possible to manufacture mid-sized
machines (called Minicomputers) which could perform
both complex scientific calculations and everyday
commercial calculations e.g. IBM 360
• Several new ideas were introduced in the OS including
i. Multiprogramming, the ability to run several
programs at the same time using memory partition
ii. Spooling, the ability to read program cards into disk
directly, and
iii. Time-sharing, a variant of multiprogramming in
which more than one user can access and use the
system at the same time
• Examples OS/360, MULTICS, UNIX
History of Operating Systems
The Fourth Generation (1980 – Present)
• The introduction of Large Scale Integrated Circuits and
Very Large Scale Integrated Circuits started a new wave
of computer technologies called Microcomputers or
Personal Computers (PCs)
• At the time, the computing industry was well developed
with distinct specializations such as processor
manufacturers (Intel) computer manufacturers (IBM,
Apple) and applications developers (Microsoft)
• Early operating systems include CP/M, DOS, MS-DOS,
and Lisa
• Current popular OS includes Windows, Mac OS, Linux,
Unix, and FreeBSD
History of Operating Systems
The Fifth Generation (1990 – Present)
• Mobile computing stems from the idea of combining
telephony and computing into one phone-like device
popularly known as a smartphone
• Symbian OS was used in the first smartphones
i. 1996 Nokia N9000
ii. 1997 Ericsson GS88 Penelope
• RIM OS released with Blackberry in 2002
• iOS released with iPhone in 2007
• Android released by Google in 2008
Types of Operating Systems
i. Batch Systems. More than one job can be stored in
main memory, e.g. Fortran Monitor System (FMS)
ii. Multiuser Systems. Jobs of different users who are
connected to a main computer are executed through
multiprogramming. Interaction of jobs with the user is
possible e.g. MULTICS, UNIX
iii. Multitasking systems. Multiple tasks of a single user
can be opened on the system through multi-
programming, e.g Windows
iv. Network systems. A user can connect to another
machine and execute tasks, e.g. Novell Netware,
Windows NT
Types of Operating Systems
v. Distributed Systems. Multiple nodes on a network can
work as one powerful machine, e.g. Amoeba, V system,
Chorus
vi. Real-Time Systems. Used to handle time-bound
responses to the applications, e.g. pSOS, VxWorks, RTLinux
vii. Embedded systems. Specialized systems with small size,
memory and power restrictions, e.g. Toshiba Pocket PC,
Palm OS, Symbian OS, iPhone OS, RIM’s BlackBerry,
Windows Phone, Linux, Android and Maemo.
Operating Systems Concepts
Most operating systems contain common and basic
concepts discussed in this section
1. A process. A process is a program in execution. A
process is associated with an address space, registers,
open files and other related process
2. Address Space. An address space is a list of memory
locations which a process is allowed to access. The
address is a 32/64-bit number starting from 0 to a
maximum.
3. A file. An abstraction of data stored in disk
4. Input/Output. OS manages the input and output
devices using I/O subsystems consisting of device
drivers
Operating Systems Concepts
5. Permission. Files access is protected using permission
assigned as a protection code to each file (The 9 bit rwx
code)
6. Shell. User interface to the Operating System. Can be
command-line or GUI based. Provides a friendly way to
submit computing requests to the OS and get responses.
7. System Call. A system call is a mechanism used by
programs to request services from the operating system
(OS). A system call is initiated by the program executing a
specific instruction, which triggers a switch to kernel mode,
allowing the program to request a service from the OS. The
OS then handles the request, performs the necessary
operations, and returns the result back to the program.
Class Work
1. What are the main functions of an operating system?
2. Discuss the history of operating systems based on
associated computer generations
3. How does UNIX differ from its predecessor MULTICS?
4. Trace back the rise of Windows as the most popular OS
5. How many lines of code does an operating system such
as Windows or Linux contain?
6. Think of an interesting OS project that you would like to
accomplish this semester
